Electromagnetic instrument tapping device

ABSTRACT

Electromagnetic apparatus for periodically tapping instruments and the like to remove static friction includes an armature and a coil supported near the armature, and means for periodically energizing the coil to generate a magnetic force which displaces the armature in one direction, with the armature being biased for displacement in the opposite direction upon deenergization of the coil, and said displacements in the one and the opposite directions providing tapping forces which are transmitted to the instrument.

[75] lnventor: DonaldJ. Abel, Franklin Lakes, NJ.

[73] Assignee: Meta Corporation, Park Ridge, NJ.

22 Filed: Apr. 2, 1974 [21] Appl. No.: 457,236

[52] US. C1 ..173/100,173/117, 173/131,

[51] Int. Cl B2501 13/00 v [58] Field oiSearchH 173/100, 117, 131; 73/432,- j 259/1 [56] References Cited UNITED STATES PATENTS 3,253,663 5/1966 Burgess, .lr 173/131 3,507,339 4/1970 De Mayo 173/100 Elite tet 11 1 1111 3, M Abel Mar. 11, 1975 1 1 ELECTROMAGNETHC ENSTRUMENT 3.S70.2l7 3/1971 Steuernugel 173/100 ppm DEVIQE 160L204 8/1971 Denley 173/101) Primary Examiner-James A. Leppink [57] ABSTRACT Electromagnetic apparatus for periodically tapping instruments and the like to remove static friction includes an armature and a coil supported near the armature, and means for periodically energizing the coil to generate a magnetic force which displaces the armature in one direction, with the armature being biased for displacement in the opposite direction upon deenergization of the coil, and said displacements in the one and the opposite directions providing tapping forces which are transmitted to the instrument.

16 C1aims,'10 Dravving Figures PATENTEW 3870.103

sum 1 [if 3 FIG. 3

PATENTEI] MARI 1 I975 SHEET 2 3 ELECTROMAGNETIC INSTRUMENT TAPPING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to electromagnetic apparatus for periodically tapping instruments and the like for removing static friction or hang up from said instruments. More particularly, this invention relates to apparatus of the type described which has fewer components, is smaller and less expensive to manufacture, provides a higher mechanical output with lower input power requirements and is more reliable than similar apparatus now known in the art.

2. Description of the Prior Art Prior art electromagnetic tapping devices such as described in US. Pat. No. 3,507,339 issued to J. P. De Mayo on Apr. 21, 1970 has been designed using several magnetic components and a plurality of magnetic flux paths. Devices of this type require relatively large electromagnetic coils and a high energizing voltage in order to generate the required tapping force. Also, heat dissipation is necessary, which precludes a reduction in the size of the device. Further, the prior art devices have included means for limiting movement of the armature and damping means have been required to avoid contact between the armature and the limiting means. Additionally, prior art designs have been such that the proximity of theseveral magnetic components has been known to cause a residual magnetism which adversely affects the tapping function of the device. All in all, the prior art devices have been less efficient and more costly to manufacture than might be desired and they have not had the precision and sensitivity of the instruments with which they are intended to be used.

SUMMARY OF THE INVENTION The present invention contemplates an instrument tapping device which overcomes the aforenoted disadvantages of the prior art. The device of the invention includes a base which is mounted on an instrument subject to static friction or the like, and which base supports a yoke. The yoke carries a coil which is periodically energized and the magnetic force thus generated displaces an armature supported near the coil in one direction for tapping the base with a force which is transmitted to the instrument. The armature is biased for being displaced in an opposite direction when the coil is deenergized, whereupon the armature again taps the base with a force which is transmitted to the instrument. The armature or the base may carry adjustable bumpers for widening the range of armature displacements and hence the range of tapping forces. In one embodiment of the invention the coil is periodically energized by pulses form a pulse-forming circuit and in other embodiments of the invention switches are mounted on the armatiire and are responsive to the armature displacement for periodically connecting a constant voltage source to the coil for energizing said coil.

One object of the invention is to provide an instrument tapping device which is more efficient, more reliable and less costly to manufacture than similar devices now known in the art.

Another object of this invention is to provide a device of the type described which requires less power than prior art devices so as to preclude the necessity for heat dissipation, whereby the device may be smaller in size than the prior art devices.

Another object of this invention is to provide a device of the type described having fewer components than the prior art devices, and to arrange said components to eliminate the effects of residual magnetism.

Another object of this invention is to provide a device of the type described which has a wide range of tapping forces.

Another object of this invention is to provide an instrument tapping device which provides tapping forces in one and opposite directions so as to double the effectivity of the device which tends to increase its life.

Another object of this invention is to provide means of the type described including a circuit for generating pulses which periodically energize a coil to generate an electromagnetic force which displaces an armature to provide a tapping force.

Another object of this invention is to bias the armature for displacement when the coil is deenergized to generate another tapping force.

Another object of this invention is to provide means of the type described including switching means responsive to the displacement of the armature for periodically connecting a constant voltage source to the coil for energizing said coil.

Another object of this invention is to provide an instrument tapping device having precision and sensitivity commensurate with the instruments with which the device is intended for use.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows taken together with the accompanying drawings wherein several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention, reference being had to the appended claims for that purpose.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of a tapping device according to the invention.

FIG. 2 is a sectional view of the device taken along the line 2-2 in FIG. 1.

FIG. 3 is a diagrammatic representation showing an embodiment of the invention wherein bumper means are carried on the armature of the device.

FIG. 4 is a diagrammatic representation showing an embodiment of the invention wherein bumper means are carried on the base of the device.

FIG. 5 is an electrical circuit diagram showing means for providing pulses for periodically energizing the coil of the device.

FIG. 6A is an electrical circuit diagram showing switching means arranged with a constant voltage source for periodically energizing the coil of the invention, and a timing capacitor in one configuration for affecting the energization cycle.

FIG. 6B is an electrical circuit diagram showning the FIG. 8 is a diagrammatic representation of another embodiment of the invention wherein the switching means of FIGS. 6A, 6B includes switch contacts and contact actuating means.

' FIG. 9 is a diagrammatic representation showing another embodiment of the invention wherein the switching means of FIGS. 6A, 6B includes a reed switch and an actuating magnet arrangement.

DESCRIPTION OF THE INVENTION With reference first to FIGS. 1, 2 and 4, the device of the invention is shown as including a base 2 which may be of brass or some other such suitable material, and which base 2 carries mounting holes 4 for mounting the base through screws or the like to an instrument such as an indicator or sensor which is subject to inertial and frictional forces, hysteresis and other sticking forces defined generally as static friction which might detract from instrument readout and accuracy.

Base 2 has a member or portion 6 extending normal to the base. A yoke 14 has an extension or shaft 10 which is journaled in base portion 6..A generally U- shaped armature 12 which may be of Armco Iron or some other such suitable material is journaled on shaft 10. Yoke '14 carries a suitably wound coil or electromagnet 16. Yoke 14 and coil 16 are shown in FIG. 4 as angularly disposed relative to armature l2, and which angular disposition is adjustable by a screw 18 (FIG. 1) which secures shaft 10 of yoke 14 to base portion 6. The angular disposition provides a predetermined magnetic path for purposes which will hereinafter become evident. A coil spring 20 is secured to armature 12 through a pin 22, and which spring is secured to shaft 10 through a hub 23.

Threaded through base 2 are a pair of screws 24 and 26 which are suitably secured through nuts 28 and 30, respectively, as best shown in FIG. 4. Screws 24 and 26 act as bumpers or stops for armature 12 when the armature is displaced about the axis of shaft 10 as will be hereinafter described, and for this purpose the screws may carry resilient cushion caps 32 and 34, respectively, which may be of rubber or a like material, to prevent metal-to-metal impact upon displacement of the armature. It will be understood that screws 24 and 26 may be adjusted to increase or decrease, i.e. define armature displacement and hence the force with which armature 12 will strike base 2 to provide the required tapping action as will be hereinafter more fully described. As shown in FIG. 4, screw 24 may be adjusted to one position so that a predetermined G force is generated as upon energization of coil 16 to displace armature 12 in one direction as indicated by the arrow, and screw 26 may be adjusted to another position so that a predetermined pull in force is generated upon energization of the coil to determine the rest or starting position of armature 12.

Armature 12 is displaced in the one direction when coil 16 is periodically energized and is displaced in the opposite direction through the restoring or biasing action of spring 20 when coil 16 is deenergized as will now be understood. The forces generated by said displacements are transmitted through base 2 to the instrument to relieve the aforenoted static friction.

Coil 16 may be energized by a pulse forming circuit such as that shown in FIG. 5. The circuit of FIG. 5 is essentially an oscillator including a pair of transistors 40 and 42, the bases of which are connected to a positive input line 44 through resistors 46 and 48, respectively, with the emitters of the transistors being connected to a negative input line 50 through diodes 52 and 54, respectively. The collector of transistor 40 is connected to positive voltage line 44 through a resistor 56 and the collector of transistor 42 is connected to positive voltage line 44 through a diode 58. Coil 16 is connected to positive input line 44 and through a capacitor 60 to the base transistor 40.

Decoupling capacitors 62 and 66 are connected across positive and negative input lines 44 and 50 and across the collector of transistor 40 and negative input line 50, respectively. A steering diode 68 is connected across input lines 44 and 50 in parallel with capacitor 62. The collector of transistor 40 is connected to the base of transistor 42 through a capacitor 64. The collector of transistor 42 is connected to negative voltage input line 50 through a capacitor 69. The circuit is connected to a power supply through positive input line 44, a resistor 70 and a rectifying diode 72, and is grounded through negative input line 50. Diode 72 permits the circuit to be operated from an a.c. power supply as well as from a dc. power. supply as will be understood by those skilled in the art.

With the circuit as shown in FIG. 5, transistors 40 and 42 are alternately conductive. When transistor 42 is conductive for example, coil 16 is deenergized, and when transistor 40 is conductive 16 is energized.

The RC characteristics of the circuit determine the intervals during which the transistors are conductive as will be understood by those skilled in the art.

The embodiment of the invention shown in FIGS. I, 2 and 4 include bumper screws 24 and 26 supported in base 2 as heretofore described. In the embodiment of the invention shown in FIG. 3, armature 12 carries adjustable bumper screws and 82 at either end thereof, and which screws may be set screws as shown in the figure. In this embodiment of the invention the upper surface 2A of plate 2 may carry a resilient coating or pad 84 of rubber or the like on at least either end thereof to cushion or prevent metal-to-metal contact between adjustable screws 80 and 82 and base 2. Screws 80 and 82 may be appropriately adjusted so that the desired G and pull-in forces are generated for purposes as heretofore described. with reference to FIGS. 1, 2 and 4.

The invention has been thusfar described with regard to the energization of coil 16 by a pulse forming circuit such as that shown in FIG. 5. In the form of the invention shown generally in FIGS. 6A and 6B, a constant voltage source shown as a battery 86 is connected to coil 16 through a switch 88 which may be initially closed, and which switch 88 is suitably supported on armature 12 by supporting means 90 so that the switch opens and closes in accordance with the displacement of the armature. Particular embodiments of this form of theinvention are shown in FIGS. 7, 8 and 9.

Thus, in FIG. 7 an electrolytic or bubble switch 89 which may be of a conventional type containing a suit able electrolyte 91 and such as that manufactured by l-Iamilin Inc., Lake Mills, Wisconsin, is supported on armature 12 by a bracket 92 secured to the armature by a screw 94. With the armature in the position as shown in the figure, switch 89 closes the circuit between battery 86 and coil 16 (FIGS. 6A, 63) to energize coil 16, whereupon armature 12 is displaced in the direction of the arrow, with switch 89 being opened after a predetermined travel of the armature to disconnect the battery from the coil. The coil is thus deenergized and the armature is displaced in the opposite direction through the action of biasing spring until switch 89 again closes the circuit. In this manner armature l2 provides the tapping action as heretofore noted with reference to FIGS. 11-4.

In the embodiment of the invention shown in FIG. 8, a contact assembly Q6 is supported on armature 12 through a screw 102. When armature 12 is in the position shown in the figure, the contact assembly is closed by arm M0 so as to connect battery 86 to coil 16, whereupon the coil is energized causing armature 12 carrying arm 100 to be displaced to open the contacts, and to thereupon deenergize the coil for providing the desired tapping action as heretofore noted with reference to FIGS. 1- Contact assembly 96 may be of the type manufactured by the H. A. Wilson Co., Union, New Jersey.

The embodimentof the invention shown in FIG. 9 features a reed switch which may be of the conventional type such as that manufactured by Wealock Signals Inc., Long Branch, New Jersey, and which switch is designated in the figure by the numeral MM. Switch 104 is mounted on base 2 by a bracket 106 secured to the base through a screw I08. Armature 12 carries a bracket in mounted thereto through a screw 112, and which bracket carries a magnet lid for operating reed switch 104 as will be understood by those skilled in the art. When armature 12 is in the position shown, reed switch I04 is effective through magnet 114 for connecting battery 36 to coil 16, whereby the coil is energized and armature 12 is diaplaced so that magnet I14 moves away from switch MM causing the switch to open and to deenergize the coil for providing the desired tapping action as heretofore described with reference to FIGS. 1-4.

With further reference to FIGS. 6A and 6B, the frequency at which coil 16 is energized and deenergized may be controlled by a capacitor 116. In FIG. 6A capacitor 116 is shown connected across coil 16 and in FIG. 6B the capacitor is connected across the battery. In either event a delaying or time lag function is provided, with the parameters of the capacitors being predetermined for providing the desired energizing and deenergizing as will be understood by those skilled in the art.

It will now be seen from the aforegoing description of the invention and the several embodiments thereof, that an instrument tapping device has been provided which is small in size and more reliable and efficient than like devices now known in the art. Specifically, the device of the present invention has fewer components so as to render it more economical to manufacture and is of a precision nature so as to have the sensitivity of the instruments with which it is intended to be used. The desired tapping action is provided twice in each cycle, i.e., once when coil or electromagnet 16 is energized and once when the coil is deenergized, so as to prevent wear and tear on the mechanical parts and to thus tend to increase the life of the device. Adjustment is easily provided for a wide range of tapping forces. Because of the construction of the device heat dissipation is not a problem and therefore the device can be presented in a small compact package.

Although several embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes may also be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art. For example, the displacement axis of armature 12 may be in a variety of positions relative to the axis of coil 16 as long as all positions of the two components complete a magnetic flux loop between the armature and coil as will now be appreciated.

What is claimed is:

1. Apparatus for periodically tapping a device of the type subject to static friction for relieving said friction, comprising:

a base adapted to be secured to the device;

an electromagnet, and means associated with the base and supporting the electromagnet;

an armature, and means supporting the armature for displacement relative to the base;

the electromagnet and armature supported in positions relative to each other to provide a predetermined magnetic path;

means periodically energizing the electromagnet to generate a magnetic force which displaces the armature in one direction to tap the base with a first force;

means biasing the armature to displace said armature in an opposite direction when the electromagnet is deenergized to tap the base with a second force; and

the first and second forces transmitted through the base to the device to relieve the static friction.

2. Apparatus as described by claim 1, including:

bumper means arranged with the base and the armature for defining the displacement of the armature in the one and the opposite directions. 3. Apparatus as described by claim 2, wherein the bumper means includes:

first means adjustably supported by the base for defining the displacement of the armature in the one direction; and

second means adjustably supported by the base for defining the displacement of the armature in the opposite direction.

4. Apparatus as described by claim 3, wherein:

the armature is displaced in the one direction to abut the first means, and said first means carries resilient means to cushion the abutment; and

the armature is displaced in the opposite direction to abut the second means, and said second means carries resilient means to cushion the abutment.

5. Apparatus as described by claim 2, wherein the bumper means includes:

first means adjustably supported by the armature for defining the displacement of the armature in the one direction; and

second means adjustably supported by the armature for defining the displacement of the armature in the opposite direction.

6. Apparatus as described by claim 5, wherein:

the armature is displaced in the one direction until the first means abuts the base, and the base carries resilient means to cushion the abutment; and

the armature is displaced in the opposite direction until the second means abuts the base, and the base carries resilient means to cushion the abutment.

7. Apparatus as described by claim 1, wherein the means associated with the base and supporting the electromagnet includes:

a base portion;

a yoke supported by the base portion;

the electromagnet supported by the yoke in a position relative to the armature to provide the prede termined magnetic path; and

means for adjusting the position of the yoke and electromagnet'for providing other predetermined magnetic paths.

8. Apparatus as described by claim 7, wherein the means supporting the armature for displacement relative to the base includes:

a shaft carried by the yoke; and

the armature journaled on the shaft for displacement relative to the base.

9. Apparatus as described by claim 8, wherein the means for adjusting the position of the electromagnet for providing other predetermined magnetic paths includes:

the shaft carried by the yoke journaled in the base portion; and

means for adjustably securing the journaled shaft in the base portion.

10. Apparatus as described by claim 8, wherein:

the biasing means includes a spring secured to the armature and to the shaft.

11. Apparatus as described by claim 1, wherein the means periodically energizing the electromagnet includes:

a pulse forming circuit connected to the electromagnet and periodically providing pulses for energizing said electromagnet.

12. Apparatus as described by claim 1, wherein the means for periodically energizing the electromagnet includes:

circuit means including a constant voltage source and switching means connected to the constant voltage source and to the electromagnet; and the switching means including means supported by the armature and responsive to the displacement thereof the periodically connecting the constant voltage source to the electromagnet to energize said electromagnet. 13. Apparatus as described by claim 12, wherein the switching means includes:

an electrolytic switch supported by the armature and responsive to the displacement thereof for periodically connecting the constant voltage source to the electromagnet to energize said electromagnet. 14. Apparatus as described by claim 12, wherein the switching means includes:

contact means supported by the base; contact actuating means arranged with the contact means and supported by the armature, and responsive to the displacement thereof for periodically actuating the contact means to connect the constant voltage source to the electromagnet to energize said electromagnet. 15. Apparatus as described by claim 12, wherein the switching means includes:

a reed switch supported by the base; and reed switch actuating means arranged with the reed switch and, supported by the armature and responsive to the displacement thereof for periodically actuating the reed switch to connect the constant voltage source to the electromagnet to energize said electromagnet. 16. Apparatus as described by claim 12, wherein the circuit means includes:

time delay means for controlling the energization of the electromagnet. 

1. Apparatus for periodically tapping a device of the type subject to static friction for relieving said friction, comprising: a base adapted to be secured to the device; an electromagnet, and means associated with the base and supporting the electromagnet; an armature, and means supporting the armature for displacement relative to the base; the electromagnet and armature supported in positions relative to each other to provide a predetermined magnetic path; means periodically energizing the electromagnet to generate a magnetic force which displaces the armature in one direction to tap the base with a first force; means biasing the armature to displace said armature in an opposite direction when the electromagnet is deenergized to tap the base with a second force; and the first and second forces transmitted through the base to the device to relieve the static friction.
 1. Apparatus for periodically tapping a device of the type subject to static friction for relieving said friction, comprising: a base adapted to be secured to the device; an electromagnet, and means associated with the base and supporting the electromagnet; an armature, and means supporting the armature for displacement relative to the base; the electromagnet and armature supported in positions relative to each other to provide a predetermined magnetic path; means periodically energizing the electromagnet to generate a magnetic force which displaces the armature in one direction to tap the base with a first force; means biasing the armature to displace said armature in an opposite direction when the electromagnet is deenergized to tap the base with a second force; and the first and second forces transmitted through the base to the device to relieve the static friction.
 2. Apparatus as described by claim 1, including: bumper means arranged with the base and the armature for defining the displacement of the armature in the one and the opposite directions.
 3. Apparatus as described by claim 2, wherein the bumper means includes: first means adjustably supported by the base for defining the displacement of the armature in the one direction; and second means adjustably supported by the base for defining the displacement of the armature in the opposite direction.
 4. Apparatus as described by claim 3, wherein: the armature is displaced in the one direction to abut the first means, and said first means carries resilient means to cushion the abutment; and the armature is displaced in the opposite direction to abut the second means, and said second means carries resilient means to cushion the abutment.
 5. Apparatus as described by claim 2, wherein the bumper means includes: first means adjustably supported by the armature for defining the displacement of the armature in the one direction; and second means adjustably supported by the armature for defining the displacement of the armature in the opposite direction.
 6. Apparatus as described by claim 5, wherein: the armature is displaced in the one direction until the first means abuts the base, and the base carries resilient means to cushion the abutment; and the armature is displaced in the opposite direction until the second means abuts the base, and the base carries resilient means to cushion the abutment.
 7. Apparatus as described by claim 1, wherein the means associated with the base and supporting the electromagnet includes: a base portion; a yoke supported by the base portion; the electromagnet supported by the yoke in a position relative to the armature to provide the predetermined magnetic path; and means for adjusting the position of the yoke and electromagnet for providing other predetermined magnetic paths.
 8. Apparatus as described by claim 7, wherein the means supporting the armature for displacement relative to the base includes: a shaft carried by the yoke; and the armature journaled on the shaft for displacement relative to the base.
 9. Apparatus as described by claim 8, wherein the means for adjusting the position of the electromagnet for providing other predetermined magnetic paths includes: the shaft carried by the yoke journaled in the base portion; and means for adjustably securing the journaled shaft in the base portion.
 10. Apparatus as described by claim 8, wherein: the biasing means includes a spring secured to the armature and to the shaft.
 11. Apparatus as described by claim 1, wherein the means periodically energizing the electromagnet includes: a pulse forming circuit connected to the electromagnet and periodically providing pulses for energizing said electromagnet.
 12. Apparatus as described by claim 1, wherein the means for periodically energizing the electromagnet includes: circuit means including a constant voltage source and switching means connected to the constant voltage source and to the electromagnet; and the switching means including means supported by the armature and responsive to the displacement thereof for periodically connecting the constant voltage source to the electromagnet to energize said electromagnet.
 13. Apparatus as described by claim 12, wherein the switching means includes: an electrolytic switch supported by the armature and responsive to the displacement thereof for periodically connecting the constant voltage source to the electromagnet to energize said electromagnet.
 14. Apparatus as described by claim 12, wherein the switching means includes: contact means supported by the base; contact actuating means arranged with the contact means and supported by the armature, and responsive to the displacement thereof for periodically actuating the contact means to connect the constant voltage source to the electromagnet to energize said electromagnet.
 15. Apparatus as described by claim 12, wherein the switching means includes: a reed switch supported by the base; and reed switch actuating means arranged with the reed switch and, supported by the armature and responsive to the displacement thereof for periodically actuating the reed switch to connect the constant voltage source to the electromagnet to energize said electromagnet. 